Production of unsaturated carbonyl compounds



Patented Dec. 2, 1952 PRODUCTION OF UNSATURATED' CARBONYL COMPOUNDSErving-Arundale, Westfield, and Henry 0. Mot.-

tern, Bloomfield, N. J., assignors' to Standard Oil Development Company,a corporation of Delaware No Drawing. Application August 22, 1949,

' Serial No. 111,774

9 Claims. 1 This invention relates to a novel catalytic process and,more particularly, to an improved method for preparing unsaturatedcarbonyl compounds.

in good yields from glycol compounds by passing thorium. The latteroxides are present in minor amounts ranging from 1 to 15 weight percent, preferably 6 to 12 weight per cent, based on the total weight ofthe combined oxides present in elyc ls over suitabl cataly i ma l thecatalyst. It has been found that from 1 to 15 It is well known that theimp dehydrogenaper cent by weight of at least one of th oxides tion ofsecon ry l h to h r p in of zirconium, cerium and thorium, based uponkBlJOIlBS ay be achieved y Passing th who the total weight of thecatalyst composition, at: elevated temperatures over substancesactgreatly improves the ti of the magnesium ng Substantially as dehydogenation catalyst oxide, zinc oxide, or beryllium oxide as a dehy-Early developments in this f eld led to the use drogenation catalyst. ofmetals such as copper, brass, etc., as catalysts The reaction obtainedby using less than 1% in this yp of reactiono hat later, Variou of thezirconium oxide, cerium oxide, or thorium difiicultly reducible metallicoxides such as zinc oxide, or mixtures thereof, is perceptible but notoxide, cerium oxide, magnesium-oxide, etc.,. atsufiicientto be of anyappreciable value, while tained considerableprominence as dehydrogenatheimprovement obtained by using more than tion. catalysts. Variouscombinations ,of catalytic 15% of theseoxides is not sufiiciently greatover metals and difiicultly reducible metallic oxides that obtained whenusing about 6 to 12% to warhave alsobeen employed. It: has been foundthat rant the additional expenditure necessary to a certain number ofthese difficultly reducible employ the material. metallic oxides have aresidual catalytic dehy- It also has been found that catalysts of thedrating efiect. as well as the above-mentioned type described can bestabilized in a desirable dehydrogenating effect, and that both effectsmay fashion by the addition thereto of. approximately be advantageouslyutilized in one over-all reac- 6 to 10% based on the weight of thezirconium tion to convert glycols to unsaturated carbonyl oxide, ceriumoxide, or thorium oxide, of a stacompounds. v bilizer selected from thegroup consisting of fer-:

An object of the present invention is to utilize ric oxide,'silicaandalumina. the dehydrogenation activity of diiilcu-ltly re- Othermetallic oxides may be advantageously ducible metallic oxide catalystssuch as magneadded to the promoted zinc oxide catalyst. The slum oxide,zinc oxide, and beryllium oxide and, presence of such stabilizers is ofespecial value at the same time, utilize the residual activity of whenthe glycol feed stock contains impurities these catalysts as dehydrationcatalysts, particuwhich cause. inactivation of the catalyst while itlarlywhenthese oxidesare employed as mixtures. is in use. For instance,the catalyst prepared Another object of this inventionisqt'o provide afromthetwo oxides may be seriously inactivated process for thepreparation of unsaturated'carby carbon. or resin deposition unlesssmall bonyl compounds from glycols by a catalytic amounts of SiOz, A1203or F8203 are also included process, wherein-the productsare relativelyclean, in the composition. This effect is particularly are easilyseparated and purified, and produced deleterious when the glycol feedstock contains in good yields from the starting materials. Theseimpurities which resinify or carbonize under the and other objects willbe apparent to those skilled 40 conditionsof the reaction. in. the artfrom the following description. There are various grades of zirconiawhich may vOnly a special class of catalysts is suited for beemployed inthe preparation of the zirconiause in this combined dehydrogenation anddenta ning catalysts of s invention a d whic hydration process. Thesecatalysts contain or are capable of both dehydrogenation'and dehyconsistessentially of a major portion of an oxide dration actions. Typicalanalyses of some of the of zinc, magnesium, or beryllium, and a. minorgrades of zirconiaj suitable for use in preparing portion of an oxide ofzirconium, cerium and these catalysts are as follows:

, a Spectroscopic Tame att 1 3553 stilt? Percent Z: 87. 97 99. 37 97.1099, 943 PercentSiOi, 8-49 0-30 1.88 0.020 Percent AizO: 0.38 0. 08 0. 520, 005 Percent MgO 0.30 0.05 0.05 0. 005 Percent NazO (a 1.50 0:02 0.020.002 Percent-T101 0.30 0.15 0. 30 0 005 Percent F620: 0.08 0.03 0.11 0,020

Q 7 i grade oi zirconia manufactured by. the'litanium Alloy-Manufacturing Company, Niagara Falls, New York;

It is believed, however, that the catalytic effect of the zirconia addedto the oxides of zinc, magnesium or beryllium, is due to the zirconiumoxide itself, and not to the impurities contained therein, althoughthere is some indication that the presence of small amounts of SiO2 maybe beneficial in giving the combined action. For this reaction, it is apreferred feature of this invention to use a zirconia promoted zincoxide catalyst containing small amounts of silica.

The preparation of the catalysts of this invention may be exemplified bythe preparation of a zinc oxide-zirconium oxide catalyst. In thepreparation of the catalyst, it is preferred to mix the two oxides inthe proper proportions in powdered form, then to work enough water intothe mixture to make a heavy slurry. This will ordinarily require avolume of water approximately equal to the volume of powder employed.The catalyst slurry is then preferably coated on a carrier. The coatingoperation may be accomplished by placing the catalyst support or carrierin a tumbling device, pouring the catalyst slurry over the carrier, andthen tumbling until a uniform thick mix is secured. The mix is thenplaced in an oven at a temperature of about 80 C. and dried. The dryingrequires approximately 24 to 48 hours. Metal turnings may be employed asthe catalyst carrier or support, or pumice in granular or pill form maybe used as well as other types of carriers which are well known in thecatalyst art. Pumice and metal turnings are preferred carriers, however,and of the metal turnings, steel or brass turnings are preferred.

These catalysts may be employed either for fixed bed operations or as apart of a fluid operation using the catalyst in a fluidized state.Nitrogen or other inert gas may be used as the fluidizing medium. Thecatalyst will need to be regenerated from time to time since a certaindegree ofcatalytic activity will tend to be'lost after a period ofconversion. The regeneration can best be accomplished by treatment ofthe spent catalyst at elevated temperatures with steam or air or with amixture of the two. At least 80% of the original activity may berestored in this manner. The catalytic and reactivating periods may bealternately repeated throughout the life of the catalyst. Certainimpurities and contaminants tend to act as poisons for the catalyst andtheir presence in the feed will substantially reduce the activity of thecatalyst. These socalled poisons include halogens, sulfur compounds suchas sulfides and mercaptans, and nitrogen compounds such as amines,nitriles, amides, and nitro compounds.

This specific catalytic reaction is particularly useful in theproduction of unsaturated carbonyl compounds from glycol type materials.It is necessary, however, that these glycols have a certain type ofstructure in order that the preferred product, the unsaturated carbonylcompound, be obtained in high yield and the formation of undesirableby-products avoided.

This catalyst may be effectively employed to convert compounds of thefollowing general formula to unsaturated carbonyl compounds:

wherein R may be hydrogen or a hydrocarbon radical, R1 is a hydrocarbonradical and a: is a small whole number of value at least 1. Thehydrocarbon radical may be an alkyl, aryl, or cycloalkyl radical suchas, for example, methyl, ethyl, propyl, butyl, phenyl, cyclohexyl, orcyclopentyl or various substituted radicals in which the substitutinggroups do not interfere with the activity of the catalyst. It ispreferred to have the hydrocarbon radicals selected from the aliphaticseries and the total molecule containing no more than ten carbon atoms,otherwise the compound is very high-boiling and gives difficulty invaporization.

There is no exact limit as to the number of carbon atoms which theglycol can have, although very high molecular weight glycols aregenerally not readily available and would also have prohibitively highboiling points.

Specific examples of representative compounds as starting feeds includethe following materials: 1,3-butanediol, 2-ethyl-1,3-hexanediol,2-methyl- 1,3-hexanediol, 1,3-pentanediol, 2,4-pentanediol, and2-methyl-l,3-butanediol.

Certain of the diols can be made by condensation of two molecules of analdehyde or ketone under alkaline conditions and subsequent reduction ofthe resulting hydroxy carbonyl compound. Where one of the hydroxylgroups of a glycol product from an aldol is tertiary, the desiredreaction to form an unsaturated compound will generally not be obtainedbut rather the catalyst will reverse the aldol. This dealdolizationprobably proceeds in two steps, that is, first the tertiary hydroxylgroup is easily dehydrated to give the olefin then the molecule splitsto give degradation products and essentially little or no unsaturatedcarbonyl compound is formed. Thus all glycol products formed from thecondensation of ketones are considered to be of no practical value foruse as feed stocks in the process since only degraded products will beisolated.

It is also advisable to avoid the use of glycol products in which thehydroxyl groups are on adjacent carbon atoms such as the glycols formedby mild oxidation or hydration of isolated double bonds since thesecompounds can only yield alpha unsaturated carbonyl compounds which areunstable and will polymerize and decompose. Thus there should be atleast one methylene group between the hydroxyl groups of the glycolcompound. Furthermore, alphaomega dihydric alcohols are of little use asthey tend to yield dialdehydes which are also unstable and generallyimpossible to isolate in the pure state. However, glycols obtained inother ways can be used as can the 1,3 type glycols obtained in by aldolcondensations of aldehydes. Such methods for obtaining suitable feedmaterials for the reaction include the reaction of olefins andformaldehyde, polyhalogenation, followed by hydrolysis of thehalogen-containing compounds with alkali and aldol condensations ofaldehydes.

To summarize, the preferred structure for the glycols to be converted tounsaturated carbonyl compounds should be a glycol having no tertiaryhydroxyl group, at least one secondary hydroxyl group, and having atleast one methylene grouping located between the hydroxyl groups.

Predictions as to the exact type of unsaturated carbonyl compounds whichwill be formed from any particular glycol of a known structure can bemade but only with a limited degree of accuracy. It is quite easy todetermine which unsaturated carbonylic compounds will be formed,although it will be unlikely that the exact ratio of amounts in whichthey are formed cannot be foreseen. Since tertiary hydroxyl groups areto be avoided, the preferred glycol feed will contain at least onesecondary hydroxyl group, the other hydroxyl group being primary orsecondary. Generally speaking, hydroxyl groups in the secondary positionare more reactive both toward dehydrogenation and dehydration. Thus,from any particular glycol it is unlikely that there will be obtainedonly one product to the exclusion of other possible products andmixtures will generally be the result with the ratio of componentsvarying, depending on the reactivity of the particular compound and onthe severity of the reaction conditions. For instance, as in. Example 1below, when the 1,3-butanediol is passed in vapor phase over a zincoxide-zirconium oxide catalyst at 750 F., a mixture of methyl vinylketone and crotonaldehyde is obtained in the. condensate from thecatalytic zone together with unreacted glycol. Similarly, two types ofproducts are obtained from Z-ethyl 1,3-hexaned-iol when it is used asthe-feed stock. The mixtures so formed can be separated into thecomponents readily by known methods, including physical separations suchas fractional distillation, and chemical means such as various types ofselective formation of derivatives. By-products of the unwanted typecompounds such as ethers, hydrocarbons, and resins and polymersrepresent only a minor part of the total diol converted and do notpresent a serious problem.

The conversion of these selected type glycols to unsaturated carbonylcompounds is accomplished by passing the glycol in vapor form through acatalyst contacting zone such as a catalyst tube or column, the catalystmass being heated to atemperature of about 400 to 1000 F., preferably500 to 800" F., as an optimum, at atmospheric. pressure, and a. feedrate of from 0.5 to. 6 volumes, preferably 1.5 to 3 volumes, of liquidglycol per volume of catalyst per hour. The catalyst used was preparedessentially by the above-described. method. Pressures above atmosphericare not desirable since increased decomposition seems to occur when thereaction.

is carried out at the higher temperatures. On the other hand, reducedpressures are generally helpful and are advantageously used inconversions involving high-boiling feed materials since productstability will be thereby promoted. If the feed and/or products tend togive extensive decomposition, it may be desirable to take a lowconversion rate and recycle to get better yields. The exact temperaturesbest employed depend somewhat on the rate of feed passed over thecatalyst, conversion rate desired, boiling point and decompositiontemperature of the feed and the activity of the catalyst. The productvapors are passed to a condenser where the mixtures of products andunreacted glycol are separated by condensation from the less readilycondensible gas consisting predominantly of hydrogen and a small amountof olefin hydrocarbon and decomposition materials.

The glycols employed in the dehydrogenation process may contain smallquantities of water up to 12% without seriously affecting the formationof the unsaturated carbonyl compound.

The following examples, intended merely for purposes of illustration andnot intended as a limitation, serve to demonstrate the effectiveness ofthe catalyst described for the combined 65." action of dehydrogenationand dehydration of glycols under the conditions indicated to. yieldunsaturatedcarbonyl compounds. The examples.

demonstrate'the effectiveness of the catalyst. to carry out the desiredreaction.

Emample 1 V 1 Vol. Iler- P o cen ercent Product cc. Con- Yield versionFraction l Methyl vinyl ketone. 305' 53. 5 66.? Fract on 2Crotonaldeliyde. 152 26. 7 33; 3 Fract1on3 Unconverted l, 3- 113 19. 8.0-.-.--

butanediol.

It can be seen that the ratio of ketone toaldehyde produced from thisfeed is of the order of 2 to 1. In order to produce the ketone, thesecondary hydroxyl group must undergo dehydrogenation while the primarygroup is dehydrated. To produce the crotonaldehyde, the primary hydroxylgroup is dehydrogenated and the secondary group becomes dehydrated.

' Example 2 8 6?" Vol. cc.

Fraction 1 1 61-110 107 Fraction 2. 110455 136 Fraction 3 155473 65Fraction 4 1 173 1 Fraction 1 contained 14 cc. of water.

The low-boiling Fraction 1 is a mixture of lowboiling decompositionproducts together with various azeotropes of these compounds with water.Fraction 2 is indicated to be 2-ethyl-l-hexene- 3-0ne which is reportedin the literature to boil at 157-159 C. The presence of low boilingimpurities have evidently lowered the boiling point of the crudefraction containing this hexene-one. Fraction 3 is indicated to beessentially a mixture of the two isomeric aldehydes, 2-ethyl-3-hexenal-l and Z-ethyl-Z-hexenal-l boiling in the range of 168-1'73 C.Fraction 4 represents the unconverted 2-ethyl-L3-butanediol which can berecycled to the catalytic zone. A relatively small portion of gaseousby-products were recovered from the catalytic zone.

Example 3 As an example of the type of glycol in which one hydroxylgroup is tertiary, 2-methyl-2,4-pentanediol was passed over the samesolid catalyst bed as that described as used in Example 1 and undersubstantially the same conditions of operation. The products, however,indicated a great deal of decomposition of starting feed and consistedpredominantly of a mixture of acetone and water and unreacted glycolwith a small amount of mesityl oxide. The acetone, no doubt, resultedfrom the dealdolization of the feed stock and its intermediate products.

What is claimed is:

1. The method of converting g'lycols to unsaturated carbonyl compoundswhich comprises passin a glycol having the structure H Rhoc111).- R

on H

in which R is a radical selected from the group consisting of hydrogenand hydrocarbon radicals, R1 is a hydrocarbon radical, and x is thewhole integer 1, in the vapor phase at 400 to 1000 F. over a catalystmixture consisting essentially of a major component A selected from thegroup consisting of zinc oxide, magnesium oxide, and beryllium oxide,and from 1 to 15 per cent by weight of a minor component B, selectedfrom the group consisting of zirconium oxide, cerium oxide, and thoriumoxide based on the total weight of the catalyst mixture.

2. A process according to claim 1 in which the catalyst contains 6 to 10weight per cent of silica, based on the weight of component B.

3. A process according to claim 1 in which the catalyst is deposited onmetal turnings as a carmen 4. A process accordin to claim 1 in which thecatalyst is maintained at a temperature of 500 to 800 F.

5. The method of producing a mixture of unsaturated carbonyl compounds,consisting essentially of crotonaldehyde and methyl vinyl ketone inwhich 1,3-butanediol is passed in vapor phase at 500 F. to 800 F. over acatalyst consisting essentially of a mixture of zinc oxide as componentA and from 1 to weight per cent zirconium 8 oxide as component B, basedon the total weight of the catalyst mixture.

6. The method according to claim 5 in which the catalyst consists of amixture of about 94 wt. ZnOz and about 6 wt. ZIOz with a small amount ofsilica, and the catalyst temperature is held at approximately 750 F.

7. The method according to claim 6 in which the catalyst is deposited onmetal turnings as a carrier.

8. The method of producing a mixture of CB unsaturated carbonylcompounds in which 2- ethyl-l,3-hexanediol is passed in vapor phase overa catalyst consisting essentially of a mixture of 94 wt. ZnOz and 6 wt.ZrOz and the catalyst temperature is held at approximately 750 F.

9. The method of producing unsaturated carbonyl compounds, whichcomprises passing a glycol containing one hydroxyl group attached to asecondary carbon atom, the other hydroxyl group being attached to aprimary carbon atom, and having a single carbon atom between the carbonatoms attached to each of the hydroxyl groups, in the vapor phase at atemperature of 500 to 800 F. into contact with a catalyst mixtureconsisting essentially of a major component A selected from the groupconsisting of zinc oxide, magnesium oxide, and barium oxide and from 6to 12 weight of a minor component B selected from the group consistingof zirconium oxide, cerium oxide, and thorium oxide based on the totalweight of the catalyst mixture.

ERVING ARUNDALE. HENRY O. MOTTERN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,813,953 Reppe July 14, 19312,042,224 Groll May 26, 1936 2,179,488 Beamer Nov. 14, 1939 2,421,554Finch et al June 3, 1947 FOREIGN PATENTS Number Country Date 337,566Great Britain Nov. 6, 1930

1. THE METHOD OF CONVERTING GLYCOLS TO UNSATURATED CARBONYL COMPOUNDSWHICH COMPRISES PASSING A GLYCOL HAVING THE STRUCTURE